In recent years, there has been an increasing need for composite materials having high fracture toughness, hardness and wear resistance for use in cutting tools, wear parts, and structural applications such as dies, turbines, nozzles, and the like. Due to their high modulus of elasticity, high hardness, and high strength, single crystal whiskers of such materials as silicon carbide have been utilized for such composites. For the cutting tool application, it is desirable that the composite have improved toughness, good strength at elevated temperatures and chemical inertness, and capable of operating at high cutting speeds.
Conventional ceramic cutting tool materials have failed to find wide application primarily due to the low fracture toughness. Ceramic materials are strong candidates but are inherently limited by this lack of fracture toughness when compared to cemented carbide cutting tools. The addition of whiskers to ceramic materials is known as a technique to improve the toughness of the ceramic composite. The advent of aluminum oxide based ceramics reinforced with silicon carbide whiskers has resulted in ceramic tools being utilized for machining hard, abrasive super alloys such as Inconel. However, prior art processes have not concentrated on matching the structural qualities of a particular type of whisker to a specific ceramic material to obtain an enhanced cutting tool. There is a need for cutting tool materials with improved toughness, chemical inertness, and a capacity to withstand high cutting speeds during machining operations.